The present invention relates to a semiconductor technology and, more particularly, to both a semiconductor device suited for a screening to be performed for warranting the reliability of the device after shipped and a semiconductor module having a plurality of semiconductor devices sealed therein.
A chip-carrier type semiconductor device adopting the MCC (i.e., Micro Carrier for LSI Chip) structure is used as a sealed body for a semiconductor pellet having a high speed circuit system and has a high packaging density because of its small package size. This chip-carrier type semiconductor device adopting the MCC structure is constructed mainly of a base substrate, a sealing cap, and a semiconductor pellet sealed in a cavity formed by the former two.
The base substrate of the chip-carrier type semiconductor device adopting the MCC structure is formed of the so-called "multi-layered ceramic substrate", which is prepared by laminating a plurality of wired sheets of mullite ceramics. The side of the base substrate, on which the semiconductor pellet is mounted, is arranged on its surface with a plurality of terminals, which are electrically connected with the individual ones of a plurality of mounting terminals arranged on the rear surface of the base substrate. The wiring of the base substrate, the terminals of the surface and the mounting terminals of the rear surface are all made of a tungsten-metallized layer, for example. The electric connections between the wirings of the different layers, between the terminals and the wirings, and between the mounting terminals and the wirings are achieved through connection holes formed in the mullite ceramic sheets and through connection hole wirings formed in the connection holes.
The aforementioned semiconductor pellet is made of a substrate of single crystalline silicon, for example, and is arranged on its element forming face with any or several kinds of semiconductor elements such as bipolar transistors, MOSFETs, resistance elements or capacity elements. The semiconductor pellet is mounted on the surface of the base substrate by the face-down method, in which its element forming face faces the surface of the base substrate. This mounting is carried out by connecting a plurality of external terminals (or bonding pads) arrayed on the element forming face of the semiconductor pellet and the plurality of terminals on the surface of the base substrate electrically and mechanically through solder electrodes (e.g., projection electrodes or CCB electrodes).
The aforementioned sealing cap is made of aluminum nitride, for example, and is adhered through a sealing agent to the peripheral area of the surface of the base substrate.
A plurality of chip-carrier semiconductor devices adopting the MCC structure are mounted on a module substrate, in which a cooling system is mounted, and they are installed together in a super computer or a large-sized computer.
The chip-carrier semiconductor device adopting the MCC structure is screened after its packaging process and at an early stage before it is shipped to a customer, so that it may be screened out at that initial stage. In short, the screening is carried out with a view to exclude the defective products, which would go out of order while being used by the customer, in advance. The screening is generally carried out by testing the functions of a packaged semiconductor device at first to eliminate the defective products, by burning in the semiconductor device selected as acceptable, and by testing the function of the burned-in device to further eliminate the defective products. The semiconductor device thus selected is shipped to the customer. The "burn-in" is to accelerate a defect, which would arise while being used by the customer, by running the chip-carrier type semiconductor device under a more severe using condition (with a load) than the using condition of the customer. For the burn-in, a higher voltage than that used in an ordinary operation of bipolar transistors is applied to a semiconductor device which is equipped with a semiconductor pellet mounting a circuit system composed mainly of the bipolar transistors, for example.
This burn-in is carried out such that the chip-carrier type semiconductor device is mounted in a testing wiring board (as called the "baby board"). The testing wiring board used is the so-called "printed circuit board (i.e., PCB)" which is formed with lead wires on the surface of an epoxy resin substrate.
The mounting of the aforementioned semiconductor device on the testing wiring board is accomplished by tentatively attaching the individual ones of the plurality of mounting terminals on the rear surface of the base substrate of the chip-carrier type semiconductor device to the plurality of terminals arrayed in the central area of the surface of the testing wiring board. The tentative attaching is performed by means of solder to effect the electric and mechanical connections.
The testing wiring board is arranged in its peripheral area with a plurality of testing terminals which are connected through lead wirings with terminals connected with the mounting terminals of the semiconductor device adopting the MCC structure. Testing styluses (or probes) connected with a tester are brought into abutment against (or contact with) those testing terminals so that the electric characteristics of the semiconductor device at the initial stage are tested by the tester at the time of the burn-in or its end. All of the terminals in the central area of the testing wiring board, the lead wirings and the testing terminals are made of Cu or a laminated layer composed mainly of Cu, for example. The testing terminals are arrayed at a larger pitch than the array pitch of the terminals at the central area of the testing wiring board with a view to retaining a surplus for the area to abut against the testing styluses and the displacement of the abutting test styluses.
The testing wiring board has a number of mounting terminals all over the rear surface of the base substrate of the aforementioned semiconductor device and adopts a multi-layered wiring structure with a view to reducing the size itself of the testing wiring board. The testing wiring board adopting the multi-layered wiring structure is formed on at least its surface and back with lead wirings such that the lead wirings on the surface and the back are electrically connected with each other through both connection holes (or through holes) formed in the testing wiring board and connection hole wirings.
The testing wiring board of this kind is made of an epoxy resin as a mother material, and its manufacturing technology is established to some extent so that it is featured by an easy production and a low production cost. In other words, the burn-in using the testing wiring board can be accomplished at a reduced cost to drop the overall manufacture cost of the aforementioned semiconductor device.
Incidentally, the chip-carrier semiconductor device adopting the MCC structure is disclosed in Japanese Patent Laid-Open No. 310139/1988, for example.